Actually, the process of fossilisation is not slow and can be done relatively quickly. All what you need is for sediments to quickly cover a dead (or an alive body - as what would have happened to Noah's Flood) and hence, fossilsation can occur rapidly; evolutionarly speaking, fossils take millions of years to fossilise a bone, but unless the bone is covered by sediments quickly, the bone will never fossilise. 
Label: Non-Sarcastic